TESTING/MATGEN/slatm7.f(3)

NAME
TESTING/MATGEN/slatm7.f

SYNOPSIS

  Functions/Subroutines
subroutine slatm7 (mode, cond, irsign, idist, iseed, d, n, rank, info)
SLATM7

Function/Subroutine Documentation

  subroutine slatm7 (integer mode, real cond, integer irsign, integer idist, integer, dimension( 4 ) iseed, real, dimension( * ) d, integer n, integer rank, integer info)

SLATM7

Purpose:

    !>
    !>    SLATM7 computes the entries of D as specified by MODE
    !>    COND and IRSIGN. IDIST and ISEED determine the generation
    !>    of random numbers. SLATM7 is called by SLATMT to generate
    !>    random test matrices.
    !>

    !>  MODE   - INTEGER
    !>           On entry describes how D is to be computed:
    !>           MODE = 0 means do not change D.
    !>
    !>           MODE = 1 sets D(1)=1 and D(2:RANK)=1.0/COND
    !>           MODE = 2 sets D(1:RANK-1)=1 and D(RANK)=1.0/COND
    !>           MODE = 3 sets D(I)=COND**(-(I-1)/(RANK-1)) I=1:RANK
    !>
    !>           MODE = 4 sets D(i)=1 - (i-1)/(N-1)*(1 - 1/COND)
    !>           MODE = 5 sets D to random numbers in the range
    !>                    ( 1/COND , 1 ) such that their logarithms
    !>                    are uniformly distributed.
    !>           MODE = 6 set D to random numbers from same distribution
    !>                    as the rest of the matrix.
    !>           MODE < 0 has the same meaning as ABS(MODE), except that
    !>              the order of the elements of D is reversed.
    !>           Thus if MODE is positive, D has entries ranging from
    !>              1 to 1/COND, if negative, from 1/COND to 1,
    !>           Not modified.
    !>
    !>  COND   - REAL
    !>           On entry, used as described under MODE above.
    !>           If used, it must be >= 1. Not modified.
    !>
    !>  IRSIGN - INTEGER
    !>           On entry, if MODE neither -6, 0 nor 6, determines sign of
    !>           entries of D
    !>           0 => leave entries of D unchanged
    !>           1 => multiply each entry of D by 1 or -1 with probability .5
    !>
    !>  IDIST  - CHARACTER*1
    !>           On entry, IDIST specifies the type of distribution to be
    !>           used to generate a random matrix .
    !>           1 => UNIFORM( 0, 1 )
    !>           2 => UNIFORM( -1, 1 )
    !>           3 => NORMAL( 0, 1 )
    !>           Not modified.
    !>
    !>  ISEED  - INTEGER array, dimension ( 4 )
    !>           On entry ISEED specifies the seed of the random number
    !>           generator. The random number generator uses a
    !>           linear congruential sequence limited to small
    !>           integers, and so should produce machine independent
    !>           random numbers. The values of ISEED are changed on
    !>           exit, and can be used in the next call to SLATM7
    !>           to continue the same random number sequence.
    !>           Changed on exit.
    !>
    !>  D      - REAL array, dimension ( MIN( M , N ) )
    !>           Array to be computed according to MODE, COND and IRSIGN.
    !>           May be changed on exit if MODE is nonzero.
    !>
    !>  N      - INTEGER
    !>           Number of entries of D. Not modified.
    !>
    !>  RANK   - INTEGER
    !>           The rank of matrix to be generated for modes 1,2,3 only.
    !>           D( RANK+1:N ) = 0.
    !>           Not modified.
    !>
    !>  INFO   - INTEGER
    !>            0  => normal termination
    !>           -1  => if MODE not in range -6 to 6
    !>           -2  => if MODE neither -6, 0 nor 6, and
    !>                  IRSIGN neither 0 nor 1
    !>           -3  => if MODE neither -6, 0 nor 6 and COND less than 1
    !>           -4  => if MODE equals 6 or -6 and IDIST not in range 1 to 3
    !>           -7  => if N negative
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 120 of file slatm7.f.

Author

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